Merging is the most common thing anyone does to a PDF, and it's also where free tools most often hide a wall — a size cap, a daily task limit, or a watermark you only discover at the download step. There's no reason for any of that when the work happens on your own machine.
Drop in as many files as you like, drag them into the order you want, and download the combined document. Because nothing is uploaded, a 300 MB stack of scans costs exactly as much to merge as a two-page memo: nothing, and no waiting on an upload bar.
You can reorder pages within the merged result before downloading, so a set of scans that came out of the feeder in the wrong sequence doesn't need a second pass through another tool. And because the merged document stays in memory, you can go straight on to compressing or signing it without re-uploading anything — which is the part that's genuinely awkward when the work happens on someone else's server.
Type into real form fields, or anywhere on a flat form.
Draw, type, or upload a signature and place it on any page.
Number the pages, with control over position and format.
Add DRAFT, CONFIDENTIAL or a logo across the pages.
Cut away white margins or crop pages down visually.
Break a document into separate files by range or interval.
Drag pages into a new order, rotate or drop the ones you don't need.
Turn sideways or upside-down pages the right way up.
Pick pages to drop, visually or by range.
Keep only the pages you want as a separate file.
Combine JPG or PNG images into one PDF, with page size control.
Render pages to images at the resolution you choose.
Shrink a PDF with a side-by-side quality preview and a size target.
Add a searchable text layer to a scanned document.
Extract text as plain text or Markdown, in reading order.